Tay-Sachs disease is a genetic disorder that is usually fatal in young children. If both parents are carriers of the disease, the probability that their offspring will develop the disease is approximately .25. Suppose that a husband and wife are both carriers and that they have three children. If the outcomes of the three pregnancies are mutually independent, what are the probabilities of the following events?
a All three children develop Tay-Sachs.
b Only one child develops Tay-Sachs.
c The third child develops Tay-Sachs, given that the first two did not.